Empirical Formula for Stress Intensity Factor of Crack Initiated from an Interface Edge

2013 ◽  
Vol 645 ◽  
pp. 377-380
Author(s):  
Zhen Yang
Keyword(s):  
Stress Intensity ◽  
Numerical Analysis ◽  
Fracture Mechanics ◽  
Stress Field ◽  
Empirical Formula ◽  
Evaluation Method ◽  
Singular Stress ◽  
Edge Singularity ◽  
Singular Stress Field ◽  
Interface Edge

Bi-material has been widely used in engineering. Due to the edge singularity, failure usually occurs from interface edge. For the evaluation of such failures, fracture mechanics approach is considered useful to avoid the edge singularity, by introducing an edge crack with various directions. However, this evaluation method is inconvenient for engineering application due to its complicity. In this paper, based on a huge amount of numerical analysis, an empirical formula of stress intensity factors (SIFs) for cracks initiated from the interface edge with various directions and crack length has been proposed. Since the cracks initiated from the interface edge is induced and dominated by the edge singular stress field, which can be characterized by the singular order and the corresponding stress intensity coefficient (SIC), this empirical formula relates their SIFs with the SIC and singular order of the edge singular stress field. With this empirical formula, it is possible to evaluate the fracture occurring from the interface edge by fracture mechanics approach, only with the numerical analysis of non-cracked bonded dissimilar materials.

Convenient Adhesive Strength Evaluation Method in Terms of the Intensity of Singular Stress Field

2018 ◽  
Vol 16 (01) ◽  
pp. 1850085 ◽  
Author(s):  
Nao-Aki Noda ◽  
Rong Li ◽  
Tatsujiro Miyazaki ◽  
Rei Takaki ◽  
Yoshikazu Sano
Keyword(s):  
Stress Field ◽  
Conventional Method ◽  
Adhesive Strength ◽  
Evaluation Method ◽  
Singular Stress ◽  
Strength Evaluation ◽  
Present Solution ◽  
Singular Stress Field

A convenient evaluation method is proposed for the debonding adhesive strength in terms of the intensity of singular stress field (ISSF) appearing at the end of interface. The same FEM mesh pattern is applied to unknown problems and reference problems. It is found that the ISSF is obtained accurately by focussing on the FEM stress at the adhesive corner. Then, the debonding condition can be expressed as a constant value of critical ISSF. The usefulness of the present solution is verified by comparing with the results of the conventional method.

Use of automated photoelasticity to determine stress intensity factors of bimaterial joints

2005 ◽  
Vol 40 (8) ◽  
pp. 785-800 ◽  
Author(s):  
B Zuccarello ◽  
S Ferrante
Keyword(s):  
Stress Intensity ◽  
Stress Field ◽  
Stress Intensity Factors ◽  
External Loading ◽  
Intensity Factors ◽  
Singular Stress ◽  
Full Field ◽  
Basic Law ◽  
Singular Stress Field ◽  
Element Approach

A new systematic experimental procedure has been developed to obtain the stress intensity factors governing the singular stress field that occurs near the intersection between the interface and free edges of bimaterial joints. A preliminary theoretical study of the singular stress field is carried out by the well-known Airy stress function method. The obtained stress laws are properly combined with the basic law of photoelasticity in order to define a procedure that permits the zone dominated by the singularity to be located and the stress intensity factors (SIFs) to be computed on the basis of full field data provided from automated photoelasticity. In particular, a systematic error analysis is used to determine the model zone where the experimental data have to be collected in order to obtain accurate SIF evaluation. As an example, the proposed method is applied to determine the SIFs of various aluminium/ PSM-1 specimens under different external loading conditions using Fourier transform photoelasticity. The experimental results have been compared to those obtained by an independent procedure, based on a boundary element approach, in order to validate the accuracy of the proposed procedure.

Effects of the Length of Carbon Nanotube (CNT) in CNT Reinforced Composites

2006 ◽  
Vol 324-325 ◽  
pp. 855-858
Author(s):  
Q. Wang ◽  
X. F. Sun ◽  
Kimihiro Ozaki
Keyword(s):  
Fracture Toughness ◽  
Carbon Nanotube ◽  
Stress Intensity ◽  
Stress Field ◽  
Stress Intensity Factors ◽  
Reinforced Composites ◽  
Intensity Factors ◽  
Singular Stress ◽  
Singular Stress Field

In this paper, the strength of the singular stress field near the ends of the CNTs in composites was analyzed to clarify the effects of the CNT length on stress filed in the CNT reinforced composites when studying the fracture toughness. The singular stress field was separated into two types of singularities, symmetric and skew-symmetric, near the ends of CNTs according to the deformation and loading types. The stress intensity factors of the singular stress field were calculated for these two types of singularities. The effects of the CNT length in CNT reinforced composites on these stress intensity factors were investigated.

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